An additive manufacturing process for manufacturing a three-dimensional object (target object) by depositing a constituent material in a layer-by-layer manner on the basis of the cross-sectional data of the target object has recently been receiving attention.
PTL 1 discloses a method in which particles serving as a constituent material (constituent particles) are arranged according to the cross-sectional data of a target object by an electrophotographic process and then thermally fused together in a layer-by-layer manner.
PTL 2 discloses a method in which a layer composed of constituent particles is formed on a base and then the constituent particles are fused together in a layer-by-layer manner by spraying a liquid binder to partially dissolve the constituent particles or by irradiating the constituent particles with a laser beam according to cross-sectional data of a target object.
When a complicated form including, for example, an overhang structure or a structure including a moving part is manufactured by the additive manufacturing process, it is necessary to form a structure on a region where a structure of a target object is absent. In this case, a support member that supports the structure is provided on the lower side of the structure in the direction of gravity. That is, the support member is formed in the region where the target object is absent in the course of the build-up, as needed.
The support member is unnecessary for the target object and thus removed after the completion of the build-up. Accordingly, the support member is desirably composed of a material that can be easily removed from a surface of the structure composed of a structural material.
In PTL 1, a laminated article is formed of particles (support material particles) containing a material constituting a support member and particles (structural material particles) containing a material that constitutes the target object and that is composed of a resin having a higher softening temperature than the support material particles after the build-up of the laminated article. After the build-up of the laminated article, the laminated article is heated to a temperature which is equal to or higher than the melting temperature of the support material particles and at which the structure is not melted to selectively melt and remove the support member, thereby providing the structure, i.e., the target object.
PTL 2 discloses a formation process with particles each including a core composed of metal, ceramic, plastic, or the like, a first coating film on the core, the first coating film being composed of a polar material, and a second coating film on the first coating film, the second coating film being composed of a surfactant. In PTL 2, steps of disposing a layer composed of the particles on a base and spraying a liquid binder on the layer, the liquid binder dissolving the first and the second coating films, or irradiating the layer with a laser beam according to a predetermined pattern are repeated to bind the particles together, thereby building up an object. A region of the particles that have not been sprayed with the liquid binder or not irradiated with the laser beam and thus are not fused with each other serves as a support member and supports a laminate of the particles to be formed into a structure.